Trevor Rushton Posted February 22, 2015 Author Share Posted February 22, 2015 We decided to spend a few days in Berlin last week; tramping around as one does we came across this shop. Now I promise that the visit was not planned and happened quite by chance, but its quite difficult to convince the Chief of the Domestic Staff that these things just happen. I resisted the hand of temptation, but did invest in some nice looking wheels that will do for the Spitfire - they are not quite scale, but they look suitably business like. My only concern is that I have only 5mm clearance between the wheel and the wheel well and am concerned that the wheels might bind given a few rough landings. Its probably a case of keeping an eye on it. I must get some oleos as well. I decided to make fabric covered elevators and rudder using a core of 1/16 balsa with 3/16 ribs added. I had a decent pdf drawing of the full size control surfaces which I reduced to scale - the outline of the kit's surfaces was pretty accurate. I have covered the surfaces with solartex but in the usual way got far too ambitious with rib tape and stitching. Net result; not happy so built a second set, which I will probably keep simple in finishing terms. The weight of the built up surfaces was within a gramme of the solid ones so I am not really sure its worth the effort unless you are going for scale realism (probably a bit OTT on this size. My Pilot has arrives from Aces of Iron - he is strictly speaking American, but by the time he is painted and set behind the canopy I really don't think anyone will notice - Aces have some brilliant painting instructions on their website so I will report back when I have done it. Sorry, he's turned himself upside down - I cant work out how to reverse him. Hope that's all of some interest. Trevor Quote Link to comment Share on other sites More sharing options...
Chas Morgan Posted February 22, 2015 Share Posted February 22, 2015 Looking good Trevor, do make sure that the pilot gas not got a thing about being up side down, it could make flying a little too exciting! Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted September 28, 2015 Author Share Posted September 28, 2015 Apologies for the radio silence; I have been pressing on with the build and lost my way a little with the forum, particularly since there was nothing very unusual about the build. I finished the Spitfire about a month ago (more or less) and she had her maiden flight on Saturday. Before I tell you how that went, here is a photo of the completed aeroplane sans cannons - I have since fitted those. The propeller is temporary; I am going to try a Xoar WW2 type. I also have to fit some u/c doors but I thought I would try it first. To my surprise she balanced without additional nose weight although I think I could have been a bit more precise on my measurements. The plan shows the maximum rearward position for the c of g; it does not give a range. (well if it does I did not find it!) but I was probably at about the rearward position. After having run the new ASP in (no problems there) I persuaded my chief test pilot to give her a run. Take off was nice and straight and lift off good although she dropped the left wing a bit just after rotation. The flying was kind of okay but I could tell that there was something not quite right; she needed a fair bit of aileron trim and turns did not look quite right so a landing was attempted - all good until a tip stall (right wing) at an altitude of about 3 feet. Net result wings separated from fuselage and a bit of damage to the undercarriage - all repairable. Altogether not a very rewarding first flight. Collective view at the field and afterwards was that the c of g was too far back, but concern was expressed over apparent lack of washout. I have been looking at this tonight and will post some more pics for advice. Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted September 28, 2015 Author Share Posted September 28, 2015 I have tried sticking a flexible ruler along the leading edge of both wings; by bending the ruler around thetip I can see that the left wing tip is just about at the same position as the main l.e. However, the other wing tip is slightly above so I guess this is slightly wash-in as opposed to wash out. The plans don't show any washout, so I suspect its not built in. I could try cutting off the tips and tilting them down a little but fillI am not very excited abut that given the amount of filling needed. The other option would be to try adding some balsa and reshaping the tips to create some wash out - the question is will this make a difference? I could set both ailerons up a little (I will do that anyway) but does anyone have any bright ideas? I will also revisit the c of g and move it forward a bit. Quote Link to comment Share on other sites More sharing options...
will -0 Posted September 29, 2015 Share Posted September 29, 2015 I wonder if just raising both ailerons a tad would do the trick. Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted September 29, 2015 Author Share Posted September 29, 2015 Thanks will-o; it might do and I will certainly try it, but having now realised the difference between the wing tips I ought at least to get them the same to start with. I was fortunate the last time and don't want to take any chances. Do you think that a couple of mm would be enough up? Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted September 29, 2015 Share Posted September 29, 2015 The picture showing your right-hand tip shows washout. I.E. the incidence of the wing at the tip should be more negative that the incidence at the wing root so that the wing root stalls before the tip. Your post seems to suggest you have washout and washin confused. If you are going to modify the wing panels for washout then you would remove material from the wing underside, not add it. I am surprised that your right wing dropped in the tip stall - however this could be down to the extra drag caused by the washout on the right panel. Personally, I would look at making the wings panels identical. One panel seems warped. From my memories of this model it is designed without any washout. Cambrian sell spare wing sets, but I can understand this might not be your preferred option. Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted September 29, 2015 Author Share Posted September 29, 2015 Thanks Alan My top picture is not helped by being inverted, but I get what you say - I have confused the issue. What I am trying to show is that if I line through the leading edge it is lower than at the tip so yes, washout - kind of . The other wing does not exhibit this difference so I agree, I should in the first instance try and get both tips to be identical. My inclination would be to mirror the left wing and tilt the ailerons up a tad as suggested by will-o. Quote Link to comment Share on other sites More sharing options...
will -0 Posted September 30, 2015 Share Posted September 30, 2015 Do you think the difference is in the wing panel or just the tip block? If it's the tip block, worst case is lopping one off,building a new one matching the other side and off you go, it's just 3 bits of wood IIRC. Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted October 1, 2015 Author Share Posted October 1, 2015 Will o it's just the tips; I might be able to laminate some soft balsa with the tip in situ and then reshape them both. since my last post I measured the tips and compared them with the plan; if I project the line of the top and bottom of the wing they should slope down 15mm from the top and up 5 from the bottom. Apart from being unequal, the slope on mine is all wrong. Pity I did not do that to start with. Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted October 3, 2015 Author Share Posted October 3, 2015 I decided to take the bandsaw to the tips and go for radical surgery. I think it will be easier to make two new ones rather than mess about. Hopefully two new tips will help improve performance. The plan shows the maximum rearward position for the centre of gravity; I have used a method for determining the correct position 25% of cord measured at 40% of the length of the distance from root to tip. This suggests that c of g needs to be 15mm further forward. I will give it a try and see what happens. I will also balance the aeroplane with wheels retracted. Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted November 1, 2015 Author Share Posted November 1, 2015 Surgery completed and wings now complete again. I rebalanced the model, this time with the u/c retracted which I should have done before. I moved the c of g forward by 9mm; this took 200g of lead, but it may give a clue as to the less than ideal first flight. However, after putting the aeroplane back together it appears that the wing seating are out; I think it must have been like it from the start but I am a bit perplexed; I would have thought that I would have sorted that when I built it. With the tail plane level ( and square to the fuselage and fin) the wings are about 2 deg out ( one side higher than the other). Not sure how to deal with that at the moment other than by remaking the fairing and seating; whichever way it's a pain to fix. The more I look at it now the more obvious it becomes. I don't know what effect it would have had on the flying performance, but it would not have helped. Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted May 2, 2016 Share Posted May 2, 2016 Hi Trevor. I have just finished building my one and I am in the process of setting up the CofG. Have you re-maidened yours yet and, did you decide on a preferred position for your CofG? I would also be interested to now what your final weight (for the Spitfire ) turned out to be - mine is going to be about 7lb once I have added a bit of nose weight. Geoff... Quote Link to comment Share on other sites More sharing options...
Trevor Rushton Posted May 4, 2016 Author Share Posted May 4, 2016 Dear Geoff, I weighed mine last night at 2.18 kg about 4.8 lbs . This includes the nose weight of 200 g. Writing this now that seems quite light by comparison with yours and I wonder if it's right. I will check it again. Due to my alignment problems with the seating and tips I have undertaken radical surgery on the airframe and it needs a bit more work to refinish the paint scheme again. I have not flown it since the less than perfect maiden so I can't tell you about c of g other than I moved it forward by 9mm from the position shown on the plan. Good luck with yours T Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted May 6, 2016 Share Posted May 6, 2016 Hi Trevor. Thanks for your reply. That weight is quite impressive if correct. Well done. Quote Link to comment Share on other sites More sharing options...
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